After the chelation and solidification of municipal solid waste incineration fly ash, there are still certain environmental hazards. Landfilling will occupy a large amount of land, and reusing can alleviate the pressure on landfill site. This article used alkali activation technology to prepare chelated fly ash mineral powder based alkali-activated cementitious material. In addition to exploring the feasibility of alkali-activated chelated fly ash, the influence of calcium oxide content on improving the performance of cementitious material was also explored. The results show that the compressive strength of solidified body is highest when calcium oxide content is 4% (mass fraction), while the compressive strength of solidified body slowly decreases when calcium oxide content exceedes 4%. The addition of calcium oxide promotes the formation of hydration products of C-S-H gel and significantly improves the compressive strength of material. Meanwhile, through leaching tests, it is found that the heavy metal leaching concentration of solidified body doped with calcium oxide is lower than that of solidified body without calcium oxide, and meets the limit values specified in “Standard for pollution control on the landfill site of municipal solid waste” (GB 16889—2008).